chore: migrate to Zig 0.17.0

[vmvarela]

Summary

Migrate sql-pipe and its embedded Parquet implementation from Zig 0.16 to Zig 0.17.0.

Zig 0.17 compatibility changes

• require Zig 0.17.0 in the top-level package and embedded Parquet package
• update CI and release workflows to Zig 0.17.0
• migrate removed array repetition syntax (**) to @splat or explicit repeated test buffers
• replace removed Allocator.dupeZ with dupeSentinel
• replace removed std.hash.crc.Crc32 paths with std.hash.Crc32
• migrate builtin.os.tag checks to builtin.target.os.tag
• migrate build argument passthrough from b.args to addPassthruArgs()
• replace the Windows REPL @cImport path with a build-system addTranslateC module
• update the documented minimum Zig version

Parquet coverage

The normal sql-pipe build does not semantically analyze every vendored Parquet path because of Zig's lazy analysis. This migration found two additional stale CRC API uses in parquet_reader.zig and column_writer.zig.

A fixture-independent zig build check step was added to the embedded Parquet build and is now exercised by top-level CI with pure-Zig codecs.

Validation

Green on Zig 0.17.0:

• Linux build, unit tests, Parquet compile check, integration tests, and CLI smoke
• macOS build, unit tests, Parquet compile check, integration tests, and CLI smoke
• Windows build, unit tests, Parquet compile check, and Windows integration smoke
• representative release cross-builds from Linux:
  • x86_64-linux-musl
  • x86_64-windows-gnu
  • aarch64-macos

The temporary cross-build workflow used for validation was removed after it passed, so it adds no permanent CI cost.

No dependency upgrades or unrelated feature changes.

Closes #254